This invention relates to a scroll compressor wherein the size of a discharge port can be varied.
Scroll compressors are becoming widely utilized in refrigerant compression applications. In a scroll compressor, a pair of scroll members each have a base with a generally spiral wrap extending from the base. The wraps interfit to define compression chambers. One of the two scroll members is caused to orbit relative to the other, and as the two orbit a refrigerant entrapped between the wraps is compressed towards a discharge port. Typically, the size of the discharge port will control the pressure ratio, or the amount of compression on the refrigerant. Thus, as a particular volume of refrigerant passes through the compressor, the relative pressure at the discharge point of the compressor is controlled by the design of the discharge port.
At times, it may be desirable to have a lower pressure ratio, and at other times it may be desirable to have a higher pressure ratio. However, to date the design of the scroll compressor has compromised between these two goals, and has only had a fixed size discharge port.
In disclosed embodiments of this invention, the size of a discharge port in a scroll compressor can be varied based upon operational conditions.
In one embodiment, a plunger is movable adjacent to the discharge port from a position where it sits flush with the base of the scroll member. In this position, the size of the discharge port is at a minimum, and a higher ratio is achieved.
The plunger is selectively movable away from the face of the base of the scroll member such that the size of the discharge port can be made significantly larger. Thus, a lower ratio would be achieved at this position at this position.
In a second embodiment, a plunger rotates, and has a surface such that as it rotates the effective size of the discharge port is varied. In the disclosed embodiment the rotating plunger has a groove on one surface which can be aligned with the port to provide a larger size port, but which can be rotated away from the port to provide a smaller size discharge port.
Appropriate controls can be incorporated into the scroll compressor, or external to the scroll compressor to direct movement of the plungers. Further, the movement of the plungers can be strictly based on conditions within the scroll compressor, such that the plunger is movable based upon pressures, etc.
Further, the movement of the plunger can be infinitely variable, could be to a plurality of discrete locations, or could be between two spaced locations. A worker in the compressor art would recognize the conditions that would cause one to want to vary the pressure ratio, and would further understand how to develop appropriate controls to determine those conditions and then the movement of the plunger.
These and other features of the present invention can be best understood from the following specification and drawings, the following which is a brief description.